Albuquerque. A rodent-borne illness is suspected in an outbreak aboard a cruise ship that has killed three people and sickened others, prompting an ongoing investigation by health authorities.

The World Health Organization said Sunday that detailed investigations are underway, including laboratory testing, epidemiological analysis, and virus sequencing.

Hantaviruses have existed for centuries, with outbreaks historically reported in Asia and Europe. In those regions, infections have been linked to hemorrhagic fever and kidney failure. In the United States, a distinct strain emerged in the early 1990s, causing a severe respiratory illness known as Hantavirus Pulmonary Syndrome.

The virus is primarily spread through contact with infected rodents or their urine, saliva or droppings, particularly when particles become airborne and are inhaled. In rare cases, human-to-human transmission has been reported.

In the US, most cases occur in Western states, with hotspots including New Mexico and Arizona, where human exposure to rodents is more likely in rural areas. The Centers for Disease Control and Prevention began tracking the virus after a 1993 outbreak in the Four Corners region.

Symptoms often begin with flu-like signs such as fever, chills, muscle aches, and headaches, making early diagnosis difficult. The illness can escalate quickly, leading to severe respiratory distress as fluid accumulates in the lungs. Symptoms typically appear one to eight weeks after exposure.

A related condition, hemorrhagic fever with renal syndrome, usually develops within one to two weeks and affects the kidneys.

Fatality rates vary depending on the strain. Hantavirus pulmonary syndrome has a mortality rate of about 35%, while hemorrhagic fever with renal syndrome ranges from 1% to 15%, according to the CDC.

There is no specific cure or targeted treatment, though early medical care improves survival chances. Researchers say many aspects of the disease remain unclear, including why symptoms vary widely among patients.

Health experts advise minimizing contact with rodents and their droppings. When cleaning contaminated areas, protective gloves and disinfectants such as bleach are recommended, while sweeping or vacuuming should be avoided to prevent airborne exposure.